How Accurate is the i1Pro 2, Anyway?
The X-Rite i1Pro 2 occupies a unique place in the color measurement world. It is the only example of a truly affordable spectophotometer. Priced at around $1,000, the i1Pro 2 costs 1/6 of the next cheapest spectroradiometer on the market. This makes it an extremely attractive product for the average consumer.
To be sure, the i1Pro 2 has some shortcomings that explain its relatively low cost.
I wanted to test the accuracy of the i1Pro 2 on several display types by comparing its measurements with a true reference instrument, in this case the Colorimetry Research CR-300. The CR-300's 2 nm optical resolution ensures its status as a reference source. Here are the results.
The xy values report the difference between the i1Pro 2 reading and the CR-300 reading. As you can see, the i1Pro 2 comes reasonably close to the reference. The worst result was with white on a Sony LED (dE 2.66). In fact, at least measured by dE, white point accuracy provided the largest error in almost every case. However, CRT and front projector (UHD) white measurements provided dE values of less than 1.0. NOTE: different dE methods will report different error values. For example, that same 2.66 Sony LED white CIE94 error is 4.7 in dEuv.
This is one of those cases in which formal testing reinforces a pre-existing opinion. If you had asked me before this test if the accuracy of the i1Pro 2 was sufficient, I would have given a two-part answer. Yes, it is sufficient for hobbyists and enthusiasts. No, it isn't sufficient for professionals. I believe that if you are charging clients for professional calibrations, then they are entitled to the accuracy provided by a 5 nm spectroradiometer.